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We have to use the stuff called 636 from IPEX. It may be a load of BS but that's the code here. Viessmann had trouble with the PP venting they had available for a while too. It seems they had to develop local testing protocols for venting that had been in use in Europe for a looooonnng time. Big waste of money if you ask me.

Yea, officially the pressure switch in the boiler is not recognized as a LWCO. We are supposed to put it above the boiler but an autovent is not required there. Where it is put depends on the system design, of course.

Whats up with the LWCO, do you just have it on a riser with an auto vent? We have to use them also and they always screw the job up.

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The LWCO is in our gas code, (when there is radiation below the boiler), even though the boiler is quite capable of shutting down in the event of loss of water. I keep thinking of not installing them, but I always end up. Always ad an air vent, works well.

The LWCO is in our gas code, (when there is radiation below the boiler), even though the boiler is quite capable of shutting down in the event of loss of water. I keep thinking of not installing them, but I always end up. Always ad an air vent, works well.

I was just wondering about the way you did it, I always put them in my primary loop and it messes with the way I want to pipe the boiler. It looks like you just put it on a riser with vent which would give you better options for the primary. We have to use them too, I didn't install one once and never got nailed.

The people inspecting resi boilers are contractors that the utility chooses and usually that means a lower rank dude as they don't get much money for the inspection. Sometimes they catch the lack of LWCO and sometimes, if they know the boiler, know there is a pressure switch inside and they pass it. It is not consistent.

There is some flexibility on where we can put the LWCO but it cannot be above a closed valve... LOL

The people inspecting resi boilers are contractors that the utility chooses and usually that means a lower rank dude as they don't get much money for the inspection. Sometimes they catch the lack of LWCO and sometimes, if they know the boiler, know there is a pressure switch inside and they pass it. It is not consistent.

There is some flexibility on where we can put the LWCO but it cannot be above a closed valve... LOL

We have an actual inspected who it he even looks at the job your lucky. I like lots of valves so I like the idea of it on a riser, I have thought about it but worried about the auto vent failing and and having issues.

VERY nice looking project! Thanks for sharing it with us.
What is the reasoning for the 3 way valves on all of the zones? You did mention that you were able to design around a single SWT so am kinda confused as to the necessity of these.

VERY nice looking project! Thanks for sharing it with us.
What is the reasoning for the 3 way valves on all of the zones? You did mention that you were able to design around a single SWT so am kinda confused as to the necessity of these.

Thanks!

The 3 way valves are diverting valves, not mixing valves. Taco part number Z075C3 http://www.taco-hvac.com/uploads/FileLibrary/100-82.pdf Our contractor requests constant circulation on the floor loops, regardless of whether we need to add heat to the floor. These valves are fairly new... quiet, very very minimal electrical load, ball valve style so zero maintenance / trouble free. I added some switches on the wall so they could turn off the pumps in the summer.